1. Field of the Invention
The present invention relates to printing, and more particularly, to a printing plate and a patterning method using the same. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for removing residuals generated when resins are printed in fabricating a liquid crystal display (LCD) device.
2. Discussion of the Related Art
Demands for flat display devices have increased as the information society has developed. Accordingly, many efforts have been made in researching and developing various types of flat display devices, such as liquid crystal display (LCD), plasma display panel (PDP), electroluminescent display (ELD), and vacuum fluorescent display (VFD). Some of these flat display devices have already been used as displays in various kinds of equipment.
Among the various types of flat display devices, liquid crystal display (LCD) devices have been most widely used due to their advantageous characteristics of thin profile, light weight, and low power consumption. Typically, LCD devices have been used as substitutes for the Cathode Ray Tube (CRT). In addition to mobile type LCD devices, such as a display for a notebook computer, LCD devices have been developed for use as computer monitors and as televisions. The key to developing LCD devices such that they continue to be used as the most attractive flat display device is dependent on whether LCD devices can implement a higher quality picture, such as a higher resolution and/or a higher luminance large-sized screen, while still maintaining light weight, a thin profile, and low power consumption.
FIG. 1 is an exploded perspective view illustrating a related art LCD device. Hereinafter, a related art LCD device will be described with reference to FIG. 1. As shown in FIG. 1, the related art LCD device 10 includes first and second substrates 1 and 2 bonded to each other with a cell gap between them, and a liquid crystal layer 3 positioned within the cell gap between the first and second substrates 1 and 2.
The first substrate 1 includes a plurality of gate lines 4 arranged along a first direction at fixed intervals and a plurality of data lines 5 arranged along a second direction perpendicular to the first direction at fixed intervals. A plurality of pixel regions P are defined by the gate and data lines 4 and 5. A plurality of electrodes 6 are arranged within the pixel regions P. A plurality of thin film transistors T are formed adjacent to where the gate lines cross the data lines. The thin film transistor applies data signals of the data lines 5 to the pixel electrodes 6 in accordance with signals supplied to the gate lines 4.
The second substrate 2 includes a black matrix layer 7 that prevents light from exiting the second substrate except at the pixel regions P, R/G/B color filter layers 8 for displaying various colors are formed to correspond to the pixel regions, and a common electrode 9 opposite to the pixel electrodes 6 on the first substrate 1.
In the aforementioned LCD device, the liquid crystal layer 3 is positioned between the first and second substrates 1 and 2 such that the liquid crystal molecules of the liquid crystal layer 3 are driven by electric fields generated between the pixel electrode 6 and the common electrode 9. In other words, an alignment direction of the liquid crystal molecules of the liquid crystal layer 3 is controlled by the induced electric fields between the pixel electrode 6 and the common electrode 9. Accordingly, light passing through the liquid crystal layer 3 may be controlled by the alignment direction of the liquid crystal molecules, thereby displaying an image.
FIGS. 2A to 2D are cross-sectional views illustrating a related art method for patterning metal using a printing method. Hereinafter, the related art method for patterning lines, such as the gate and data lines in the related art LCD device, will be described with reference to FIGS. 2A to 2D. As shown in FIG. 2A, a metal layer 21 is deposited across the entire surface of the substrate 20. As shown in FIG. 2B, a transparent printing plate 30 having concaves 31 on a predetermined surface of a base substrate 35 is provided. The concaves 31 are filled with resins 32.
As shown in FIG. 2C, the transparent printing plate 30 is positioned to correspond to the substrate 20 so that the resins 32 of the transparent printing plate 30 are transferred onto the metal layer 21 on the substrate 20. Thus, as shown in FIG. 2D, the resins 32 from the concaves 31 remain on the metal layer 21. However, some residual resins 32a may also be printed between the remaining resins 32 on the metal layer 21. Such residual resins 32a may cause problems.
FIG. 3A and FIG. 3B are cross-sectional views illustrating residual resins generated by the related art method for patterning metal using a printing method.
As shown in FIG. 3A, the metal layer 21 is patterned by an etching process using the resins 32 as masks. When residual resins remain, a proper metal pattern 21a corresponding to a width of the remaining resin 32 can not be formed. Because the residual resins 32a are recognized as masks during the etching process, a metal residual 21b remains below the residual resin 32a after etching. Further, as shown in FIG. 3B, if the resins 32 are connected with one another by the residual resins 32a, the metal layer below adjacent resins 32 and the residual resin 32a between the adjacent resins 32 is etched to form a metal pattern 21c below the adjacent resins 32 and the residual resin 32a between the adjacent resins 32. The metal pattern 21c is formed in a single body without isolation. In this case, one metal pattern is formed incorrectly connecting one line with another line causing line shorting.
The related art patterning method also has the following problems. The residual resins can cause poor color characteristics and a step difference when the color resins are patterned for the color filter layers. Such a step difference causes a non-uniform cell gap, thereby generating a spot on the display panel.